Semiconductor device and semiconductor device manufacturing method

ABSTRACT

The present invention relates to a semiconductor device manufacturing method for forming an interlayer insulating film containing a coating insulating film having a low dielectric constant. In construction, there are provided the steps of preparing a substrate  20  on a surface of which a coating insulating film  26  is formed by coating a coating liquid containing any one selected from a group consisting of silicon-containing inorganic compound and silicon-containing organic compound, and forming a protection layer  27  for covering the coating insulating film  26  by plasmanizing a first film forming gas to react, wherein the first film forming gas consists of any one selected from a group consisting of alkoxy compound having Si—H bonds and siloxane having Si—H bonds and any one oxygen-containing gas selected from a group consisting of O 2 , N 2 O, NO 2 , CO, CO 2 , and H 2 O.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a semiconductor device and asemiconductor device manufacturing method and, more particularly, asemiconductor device and a semiconductor device manufacturing method forforming an interlayer insulating film containing a coating insulatingfilm having a low dielectric constant.

[0003] 2. Description of the Prior Art

[0004] In recent years, the multi-layered wiring structure using theinterlayer insulating film having the low dielectric constant isemployed with the higher integration degree and the higher density ofthe semiconductor integrated circuit devices. In such case, the coatinginsulating film that is excellent in flatness and has the low relativedielectric constant is often employed as the interlayer insulating film.

[0005] The coating insulating film having the low relative dielectricconstant can be obtained by coating the coating liquid containing thesilicon-containing inorganic compound or the coating liquid containingthe silicon-containing organic compound on the film forming surface bythe spin coating method and then removing the solvent in the coatingliquid by the heating.

[0006] However, the coating insulating film contains a large amount ofmoisture in the film and has the high hygroscopicity. Also, the strengthof the coating insulating film itself is relatively low. Since thecoating insulating film has a poor adhesiveness with a CVD (ChemicalVapor Deposition) film or a metal wiring layer, there is a fear ofresulting in peeling-off of the film.

[0007] In order to compensate the weak point of the coating insulatingfilm, such a structure is often employed that a cap layer (upperprotection layer) and a liner layer (lower protection layer) containingSi and N or Si and C are formed on and under the coating insulating filmto wrap the coating insulating film therein.

[0008] The semiconductor device having a multi-layered wiring comprisesan interlayer insulating film that is formed between the upper and lowerwirings by laminating in order the lower protection layer containing Siand N or Si and C, the coating insulating film and the upper protectionlayer containing Si and N or Si and C.

[0009] However, since the insulating film containing Si and N has a highrelative dielectric constant, the entire interlayer insulating filmresults in having a higher dielectric constant even if employing thelower and upper protection layers of thinner thickness.

[0010] It is difficult for the lower and upper protection layerscontaining Si and C to sufficiently suppress an increase of a leakagecurrent while the lower and upper protection layers containing Si and Chave lower relative dielectric constants than the lower and upperprotection layers containing Si and N.

[0011] In addition, it is impossible to say that the adhesivenessbetween the coating insulating film and the lower and upper protectionlayers containing Si and N or Si and C is good, and thus the barriercharacteristic to the moisture, etc. is not perfect.

[0012] On the other hand, there is an occasion where the other lower andupper protection layers are formed on the lower and upper surfaces ofthe coating insulating film using a plasma enhanced chemical vapordeposition method (hereinafter, referred to as PE-CVD method). PE-CVDmethod is capable of film-forming at a relatively lower range oftemperature while using a gas containing SiH₄ and N₂O, a gas containingSiH₄ and O₂, or a gas containing TEOS and O₂ as a film-forming gas inorder to improve the adhesiveness.

[0013] However, in the other lower and upper protection layers, thereare problems as follows for the reasons why the adhesiveness to thecoating insulating film and a mechanical strength of the film itself isnot sufficient, and a gas having a strong oxidizing reaction isemployed.

[0014] (i) There arises the peeling-off of the coating insulating filmat an interface between the coating insulating film and the lower orupper protection layer.

[0015] (ii) The laminated structure in the semiconductor device isdestroyed through the destroy of the lower protection layer as a stopperwhich serves as a framework (for reinforcement) during processing,especially CMP (Chemical mechanical Polishing).

[0016] (iii) At a formation of the upper protection layer, the usage ofthe film-forming gas including the gas having the strong oxidizingreaction results in an increase of the dielectric constant due to anoxidization of the coating insulating film.

SUMMARY OF THE INVENTION

[0017] It is an object of the present invention to provide asemiconductor device and a semiconductor device manufacturing method, ina cover insulating film constituted by a coating insulating film and aprotection layer for covering an upper surface or a lower surface of thecoating insulating film, or in an interlayer insulating film constitutedby a coating insulating film and a protection layer for covering anupper surface and a lower surface of the coating insulating film,capable of forming the cover insulating film or the interlayerinsulating film that can achieve a lower dielectric constant as a whole,has a more complete barrier characteristic to the moisture, or theleakage current, etc., and is excellent in flatness.

[0018] It is another object of the present invention to provide asemiconductor device and a semiconductor device manufacturing methodcapable of improving an adhesiveness between the protection layer andthe coating insulating film and a mechanical strength of the protectionlayer itself.

[0019] Advantages that are achieved by a configuration of the presentinvention will be explained as follows.

[0020] In the present invention, a protection layer is formed to cover acoating insulating film by plasmanizing a first film forming gas toreact, wherein the first film forming gas consists of any one selectedfrom a group consisting of alkoxy compound having Si—H bonds andsiloxane having Si—H bonds and any one oxygen-containing gas selectedfrom a group consisting of O₂, N₂O, NO₂, CO, CO₂, and H₂O.

[0021] According to the experiment made by the inventors of the presentinvention, it is found that the silicon-containing insulating filmformed by plasmanizing the first film forming gas to react has a goodadhesiveness to the coating insulating film, is dense to the same extentas the silicon nitride film, is excellent in the water resistance, andcontains the small content of moisture in the film.

[0022] In this manner, the plasma CVD insulating film according to thepresent invention has the good adhesiveness to the coating insulatingfilm and also has the density equivalent to the silicon nitride film.Therefore, when the plasma CVD insulating film according to the presentinvention is formed to come into contact with the coating insulatingfilm and to cover the coating insulating film like the configuration ofthe present invention, there can be obtained the cover insulating filmthat can have the more complete barrier characteristic to the enteringof the moisture into the coating insulating film from the outside and tothe flowing-out of the moisture to the outside, while being excellent inflatness.

[0023] Also, the plasma CVD insulating film according to the presentinvention has the lower relative dielectric constant than the siliconnitride film in addition to the above characteristics. The protectionlayer made of the plasma CVD insulating film according to the presentinvention are formed on at least any one of an upper surface and a lowersurface of the coating insulating film which serves as the main coverinsulating film or the main interlayer insulating film and has the lowrelative dielectric constant. There can be obtained the cover insulatingfilm or interlayer insulating film that has more completely the barriercharacteristic to the entering/flowing-out of the moisture into/from thecoating insulating film, the barrier characteristic to the leakagecurrent, etc. and also achieves the low dielectric constant as a whole.

[0024] In this manner, according to the present invention, there can beobtained the cover insulating film or interlayer insulating film thatcan achieve the lower dielectric constant as a whole, has a barriercharacteristic to the entering/flowing-out of the moisture into/from thecoating insulating film and a barrier characteristic to the leakagecurrent, etc. more completely, and is excellent in flatness.

[0025] The silicon-containing insulating film of the present inventionhas a peak of the absorption intensity of the infrared rays in a rangeof the wave number 2270 to 2350 cm⁻¹, a film density in a range of 2.25to 2.40 g/cm³, and a relative dielectric constant in a range of 3.3 to4.3.

[0026] According to the experiment of the inventors of this application,it is found that the silicon-containing insulating film having suchcharacteristics has the high mechanical strength, is dense, is excellentin the water resistance, and has the small amount of contained moisturein the film like the silicon nitride film, and has the relativedielectric constant smaller than the silicon nitride film. Further, itis found that the silicon-containing insulating film has a goodadhesiveness to the coating insulating film.

[0027] Therefore, if the silicon-containing insulating film havingaforementioned characteristics is employed as the protection layer forcovering the wirings, etc., the corrosion of the wiring can be preventedby blocking a penetration of the incoming moisture into thesemiconductor device, while the parasitic capacitance between thewirings can be reduced.

[0028] Also, the upper and lower wirings and the interlayer insulatingfilm interposed between the upper and lower wirings are provided on thesubstrate. The interlayer insulating film is constructed by laminatingin order from the bottom the lower protection layer formed of thesilicon-containing insulating film according to the present invention,the main insulating film, and the upper protection layer formed of thesilicon-containing insulating film according to the present invention.

[0029] The silicon-containing insulating film having aforementionedcharacteristics has a good adhesiveness with the coating insulatingfilm, and has the high mechanical strength. Therefore, the laminatedstructure is prevented from a destroy such as a peeling-off of thefilms, etc., even if a mechanical shock is applied to the laminatedstructure from outside.

[0030] The silicon-containing insulating film having aforementionedcharacteristics is dense. Therefore, the moisture contained in thecoating insulating film can be prevented from flowing out to theperipheral portions of the silicon-containing insulating film.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031]FIG. 1 is a side view showing a configuration of the plasma CVDfilm forming apparatus employed in a film forming method according to afirst embodiment of the present invention;

[0032]FIG. 2A to FIG. 2E are sectional views showing structures ofsamples employed to examine characteristics of a silicon-containinginsulating film that is formed by the film forming method according tothe first embodiment of the present invention, and structures ofcomparative samples;

[0033]FIG. 3A and FIG. 3B are tables showing examined results of a filmdensity of the insulating film that is formed by the film forming methodaccording to the second embodiment of the present invention using thesample of FIG. 2A;

[0034]FIG. 4 is a graph showing examined results of a moisture contentand a water resistance of the silicon-containing insulating film that isformed by the film forming method according to a second embodiment ofthe present invention using the sample of FIG. 2A;

[0035]FIG. 5A is a graph showing examined results of an infraredabsorption intensity of the silicon-containing insulating film that isformed by the film forming method according to a second embodiment ofthe present invention using the sample of FIG. 2A;

[0036]FIG. 5B is a graph showing examined results of an infraredabsorption intensity of the silicon-containing insulating film using thecomparative sample of FIG. 2A;

[0037]FIG. 6 is a graph showing examined results of a water resistanceof the silicon-containing insulating film that is formed by the filmforming method according to a second embodiment of the present inventionusing the sample of FIG. 2B;

[0038]FIG. 7 is a graph showing examined results of a water resistancedue to a pressure-cooker test of the silicon-containing insulating filmthat is formed by the film forming method according to a secondembodiment of the present invention using the sample of FIG. 2B;

[0039]FIG. 8 is a table showing examined results of an adhesiveness ofthe silicon-containing insulating film, that is formed by the filmforming method according to the second embodiment of the presentinvention, to a coated insulating film using the sample of FIG. 2C;

[0040]FIG. 9 is a graph showing examined results of a defect generatingrate due to a heat cycle using the sample of FIG. 2D according to thesecond embodiment of the present invention;

[0041]FIG. 10 is a graph showing examined results of a barriercharacteristic to a copper of the silicon-containing insulating filmthat is formed by the film forming method according to the secondembodiment of the present invention;

[0042]FIGS. 11A and 11E are sectional views showing a semiconductordevice manufacturing method according to a third embodiment of thepresent invention;

[0043]FIGS. 12A to 12D are sectional views showing a semiconductordevice manufacturing method according to a fourth embodiment of thepresent invention; and

[0044]FIG. 13 is a sectional view showing a semiconductor devicemanufacturing method according to a fifth embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] Embodiments of the present invention will be explained withreference to the accompanying drawings hereinafter.

[0046] (First Embodiment)

[0047]FIG. 1 is a side view showing a configuration of theparallel-plate type plasma CVD film forming apparatus 101 employed in afilm forming method according to an embodiment of the present invention.

[0048] This plasma CVD film forming apparatus 101 comprises a filmforming portion 101A that is the place at which a silicon-containinginsulating film is formed by the plasma gas on a substrate 20, and afilm forming gas supplying portion 101B having a plurality of gas supplysources constituting film forming gases.

[0049] As shown in FIG. 1, the film forming portion 101A has a chamber 1whose pressure can be reduced, and the chamber 1 is connected to anexhausting device 6 via an exhaust pipe 4. A switching valve 5 forcontrolling the open and the close between the chamber 1 and theexhausting device 6 is provided in the middle of the exhaust pipe 4. Apressure measuring means such as a vacuum gauge (not shown) formonitoring the pressure in the chamber 1 is provided to the chamber 1.

[0050] A pair of an upper electrode (a first electrode) 2 and a lowerelectrode (a second electrode) 3 opposing each other are provided to thechamber 1. A high frequency power supply (RF power supply) 7 forsupplying a high frequency power having a frequency of 13.56 MHz isconnected to the upper electrode 2, while a low frequency power supply 8for supplying a low frequency power having a frequency of 380 kHz isconnected to the lower electrode 3. The film forming gas is plasmanizedby supplying the power to the upper electrode 2 and the lower electrode3 from these power supplies 7, 8. The upper electrode 2, the lowerelectrode 3, and the power supplies 7, 8 constitute the plasmagenerating means for plasmanizing the film forming gas.

[0051] As the plasma generating means, there are the means forgenerating the plasma by the first and second electrodes 2, 3 of theparallel-plate type, the means for generating the plasma by ECR(Electron Cyclotron Resonance) method, the means for generating thehelicon plasma by irradiating the high frequency power from the antenna,etc., for example.

[0052] The upper electrode 2 is also used as a film forming gasdistributor. A plurality of through holes are formed in the upperelectrode 2, and opening portions of the through holes in the surfaceopposing to the lower electrode 3 serve as discharge ports (inlet ports)of the film forming gas. The discharge ports of the film forming gas,etc. are connected to the film forming gas supplying portion 101B via apipe 9 a. Also, a heater (not shown) may be provided to the upperelectrode 2, as the case may be. This is because, if the upper electrode2 is heated at the temperature of almost 100° C. during the filmformation, particles made of reaction products of the film forming gas,etc. can be prevented from sticking onto the upper electrode 2.

[0053] The lower electrode 3 is also used as a loading table for thesubstrate 20. A heater 12 for heating the substrate 20 on the loadingtable is provided to the lower electrode 3.

[0054] In the film forming gas supplying portion 101B, a supply sourcefor the alkoxy compound having Si—H bonds; a supply source for thesiloxane having Si—H bonds; a supply source for any oneoxygen-containing gas selected from a group consisting of oxygen (O₂),nitrogen monoxide (N₂O), nitrogen dioxide (NO₂), carbon monoxide (CO),carbon dioxide (CO₂), and water (H₂O); a supply source for the hydrogen(H₂); and a supply source for the nitrogen (N₂) are provided.

[0055] As for the alkoxy compound having Si—H bonds or the siloxanehaving Si—H bonds as the film forming gas to which the present inventionis applied, followings may be employed as the typical examples.

[0056] (i) alkoxy compound having Si—H bonds trimethoxysilane (TMS:SiH(OCH₃)₃)

[0057] (ii) siloxane having Si—H bonds tetramethyldisiloxane (TMDSO:(CH₃)₂HSi—O—SiH(CH₃)₂)

[0058] These gases are supplied appropriately to the chamber 1 of thefilm forming portion 101A via branch pipes 9 b to 9 f and a pipe 9 a towhich all branch pipes 9 b to 9 f are connected. Flow rate controllingmeans 11 a to 11 e and switching means 10 b to 10 k for controlling theopen and the close of the branch pipes 9 b to 9 f are provided in themiddle of the branch pipes 9 b to 9 f. A switching means 10 a forcontrolling the open and the close of the pipe 9 a is provided in themiddle of the pipe 9 a. Also, in order to purge the residual gas in thebranch pipes 9 b to 9 e by flowing the N₂ gas, switching means 101 to 10n, 10 p for controlling the open and the close between the branch pipe 9f, that is connected to the N₂ gas supply source, and remaining branchpipes 9 b to 9 e are provided. The N₂ gas purges the residual gas in thepipe 9 a and the chamber 1 in addition to the branch pipes 9 b to 9 e.

[0059] According to the film forming apparatus 101 described above, thesupply source for supplying at least any one of the alkoxy compoundhaving Si—H bonds and the siloxane having Si—H bonds and theoxygen-containing gas supply source are provided, and also the plasmagenerating means 2, 3, 7, 8 for plasmanizing the film forming gas areprovided.

[0060] The insulating film containing Si, O, C, H can be formed by theplasma CVD method by using the above plasma CVD equipment. Therefore, asshown in a second embodiment described in the following, it is possibleto form the insulating film that has the low dielectric constant, hasthe small amount of moisture content, is dense and is excellent in waterresistance. Also, this insulating film has the good adhesiveness to theorganic coating insulating film or the inorganic coating insulatingfilm, and has the higher capability for preventing the diffusion ofcopper (Cu).

[0061] In particular, the power supplies 7, 8 for supplying the powershaving two high and low frequencies to the first and second electrodes2, 3 of parallel-plate type respectively are connected to them.Therefore, the plasma can be generated by applying the powers havingthese two high and low frequencies to the electrodes 2, 3 respectively.Thus, the insulating film formed in this manner is dense.

[0062] (Second Embodiment)

[0063] The examination made by the inventors of the present inventionfor the silicon-containing insulating film that is formed by the aboveplasma CVD equipment will be explained hereunder.

[0064] First, the well-known parallel-plate type plasma CVD equipment isemployed as the above plasma CVD equipment. The lower electrode 3 of theupper and lower electrodes 2, 3 is also used as a substrate holder, andthe heater 12 for heating the substrate is built in the lower electrode3.

[0065] (Formation of Samples)

[0066]FIGS. 2A to 2E are sectional views showing samples having asilicon oxide film (a silicon-containing insulating film) of the presentinvention.

[0067] As shown in FIG. 2A, a sample S1 has the silicon oxide film (thismeans the silicon-containing insulating film, and referred to as a“PE-CVD TMS SiO₂ film” hereinafter) 42 a, that is formed by the PE-CVDmethod using the film forming gas containing trimethoxysilane (TMS) on asilicon substrate 41. For the sake of comparison, a comparative sampleCS1 having a silicon oxide film (referred to as a “PE-CVD TEOS SiO₂film” hereinafter) 51 a, that is formed by the PE-CVD method using thefilm forming gas containing tetraethoxysilane (TEOS) on the siliconsubstrate 41, and a comparative sample CS2 having a silicon oxide film(referred to as a “PE-CVD SiH₄ SiO₂ film” hereinafter) 52 a, that isformed by the PE-CVD method using the film forming gas containingmonosilane (SiH₄) on the silicon substrate 41, are prepared.

[0068] As shown in FIG. 2E, a sample S1A is formed by further forming anelectrode 45 on the PE-CVD TMS SiO₂ film 42 a, in the sample S1 in whichthe PE-CVD TMS SiO₂ film 42 a is formed on the silicon substrate 41. Themercury probe is employed as the electrode 45, and a contact areabetween the mercury probe and the PE-CVD TMS SiO₂ film 42 a is 0.0230cm².

[0069] As shown in FIG. 2B, samples S2, S3 are formed by forming a BPSGfilm 43 having an amount of contained phosphorus of 7 mol % and a filmthickness of about 500 nm and a PE-CVD TMS SiO₂ film 42 b to be testedin sequence on the silicon substrate (Si substrate) 41. A film thicknessof the PE-CVD TMS SiO₂ film 42 b is set to 100 nm in the sample S2, anda film thickness of the PE-CVD TMS SiO₂ film 42 b is set to 200 nm inthe sample S3. For comparison, a comparative sample CS3 employing aPE-CVD TEOS SiO₂ film 51 b having a film thickness of 200 nm in place ofthe PE-CVD TMS SiO₂ film 42 b, a comparative sample CS4 employing aPE-CVD SiH₄ SiO₂ film 52 b having a film thickness of 200 nm similarly,and a comparative sample CS5 employing a silicon nitride film (referredto as a “PE-CVD SiN film” hereinafter) 53, that is formed by the plasmaCVD method using the film forming gas containing SiH₄, NH₃ and N₂similarly to have a film thickness of 200 nm, are prepared.

[0070] As shown in FIG. 2C, samples S4, S5 are formed by forming lowdielectric constant insulating films 44 a, 44 b and a PE-CVD TMS SiO₂film 42 c in sequence on the silicon substrate (Si substrate) 41. Aninorganic coating insulating film 44 a is employed as the low dielectricconstant insulating film in the sample S4, and an organic coatinginsulating film 44 b is employed similarly in the sample S5. Forcomparison, comparative samples CS6, CS7 employing a PE-CVD TEOS SiO₂film 51 c in place of the PE-CVD TMS SiO₂ film 42 c are formed. Theinorganic coating insulating film 44 a is employed as the low dielectricconstant insulating film in the comparative sample CS6, and the organiccoating insulating film 44 b is employed similarly in the comparativesample CS7.

[0071] The inorganic coating insulating film is such an insulating filmthat is formed by coating the coating liquid such as HSQ (product name:manufactured by Dow Corning Co., Ltd.), MSQ (product name), R7 (productname: Hitachi Chemical Co., Ltd.), etc. The compound having one carbonor less is distinctively contained as the component compound in thecoating liquid. The organic coating insulating film is formed by coatingthe coating liquid such as FLARE (product name: manufactured by AlliedSignal Co., Ltd.), SiLK (product name: manufactured by The Dow ChemicalCo.), etc. The compound having two carbons or more is distinctivelycontained as the component compound in the coating liquid.

[0072] As shown in FIG. 2D, a sample S6 is formed by forming a PE-CVDTMS SiO₂ film (lower protection layer) 42 d having a film thickness ofabout 150 nm, a coating insulating film (main insulating film) 44chaving a film thickness of about 200 nm, and a PE-CVD TMS SiO₂ film(upper protection layer) 42 e having a film thickness of about 200 nm insequence on the silicon substrate 41. The coating insulating film 44 cis formed by spin-coating the coating liquid (FOx (product name)), thatis produced by dissolving HSQ (Hydrogen silsesquioxane) into thesolvent, then baking the coated liquid at the temperature of 150, 200,and 350° C. for one minute in the nitrogen respectively, and then curingthe resultant at the temperature of 400° C. for 50 minutes in thenitrogen. For comparison, a comparative sample CS8 in which a PE-CVDTEOS SiO₂ film 51 d is formed in place of the PE-CVD TMS SiO₂ film 42 das the lower protection layer and a comparative sample CS9 in whichPE-CVD TEOS SiO₂ films 51 d, 51 e are formed in place of the PE-CVD TMSSiO₂ films 42 d, 42 e as the upper and lower protection layers areprepared.

[0073] The PE-CVD TMS SiO₂ films 42 a to 42 e of the samples S1 to S6are formed by using the above plasma CVD equipment under following filmforming conditions.

[0074] Film forming gas: TMS+N₂O

[0075] TMS gas flow rate: 100 sccm

[0076] N₂O gas flow rate: 3000 sccm

[0077] Gas pressure: 0.7 Torr

[0078] Plasmanizing conditions

[0079] Power density applied to the upper electrode 2: 0.3 W/cm²

[0080] (frequency 13.56 MHz)

[0081] Power density applied to the lower electrode 3: 0.3 W/cm²

[0082] (frequency 380 kHz)

[0083] In this film-forming apparatus, these power densities correspondto the applied powers 750W to the electrodes, respectively.

[0084] Substrate temperature: 300 to 400° C.

[0085] Film forming thickness: t nm

[0086] The above plasma CVD apparatus 101 is also employed for formingthe PE-CVD TEOS SiO₂ film 51 a of the comparative sample CS1, the PE-CVDSiH₄ SiO₂ film 52 a of the comparative sample CS2, the PE-CVD TEOS SiO₂films 51 b to 51 e of the comparative samples CS3, CS4, CS6 to CS9, thePE-CVD SiN film 53 of the comparative sample CS5.

[0087] Following characteristics of the PE-CVD TMS SiO₂ film 42 a to 42e formed as above are examined.

[0088] (i) Basic characteristic

[0089] The film forming rate of the above film forming conditions is atthe range of about 160 to 170 nm/min.

[0090] Also, the refractive index of the formed PE-CVD TMS SiO₂ film isat the range of 1.477 to 1.48, and the film stress is −250 Mpa or3.0×10⁹ dyne/cm². The ellipsometer using the He—Ne laser having awavelength of 6338 angstrom is employed to measure the refractive index.Also, the optilever laser scanning system is employed to measure thefilm stress.

[0091] Also, the film thickness (t) is 500 nm, and the relativedielectric constant of the PE-CVD TMS SiO₂ film is 3.9. The sample C1Ais employed as a sample to examine the relative dielectric constant.

[0092] The relative dielectric constant is calculated based on theresult that is obtained by superposing a small signal having a frequencyof 1 MHz onto the DC voltage (V) applied between the Si substrate 41 andthe electrode 45 in the examined sample S1A, and then measuring thechange in a capacitance (C) in response to the change in the DC voltage(V).

[0093] (ii) Concentration of Carbon and Nitrogen in the film

[0094] A concentration of carbon and nitrogen in the PE-CVD TMS SiO₂film 42 a is measured by the auger electron spectroscopy method (AESmethod) using the sample S1.

[0095] According to the measuring results, the concentration of carbonis 1.0 atoms%, and the concentration of carbon is 2.1 atoms%.

[0096] (iii) Film density

[0097] The film density of the PE-CVD TMS SiO₂ film 42 a is examinedemploying the sample S1 by the well-known X-ray interference method orweight measuring method.

[0098] By way of comparison, similar examinations are carried out to thethermal SiO₂ film, the comparative sample CS1 of the PE-CVD TEOS SiO₂film 51 a, and the comparative sample CS2 of the PE-CVD SiH₄ SiO₂ film52 a in place of the PE-CVD TMS SiO₂ film 42 a.

[0099] As shown in FIGS. 3A and 3B, it is found that the PE-CVD TMS SiO₂film 42 a has the high film density of 2.33 rather than other insulatingfilms and is dense.

[0100] (iv) Moisture content in the film

[0101] An amount of contained moisture in both the film that is obtainedimmediately after the formation (as deposited) and the film that is leftfor two weeks in the air is measured employing the sample S1 by the TDS(Thermal Desorption Mass Spectroscopy) method. This TDS method is theway of heating the sample and then measuring the molecules emitted fromthe sample. For the sake of comparison, the similar examination iscarried out to the comparative sample CS1 employing the PE-CVD TEOS SiO₂film 51 a.

[0102] The examination is carried out by heating the sample from theroom temperature to 800° C. by the TDS analysis equipment and thenquantitating the amount of moisture extracted from the sample.

[0103]FIG. 4 is a graph showing the examined results. In FIG. 4, anordinate denotes the amount of moisture (wt%) represented in a linearscale and an abscissa denotes the temperature (° C.) represented in alinear scale.

[0104] According to the measurement executed immediately after the filmformation (as deposited), when the temperature is risen from the roomtemperature to 800° C., the amount of moisture in the PE-CVD TMS SiO₂film 42 a is 0.11 wt % whereas the amount of moisture in the PE-CVD TEOSSiO₂ film 51 ais 0.49 wt %. In addition, according to the measurementexecuted two weeks later, the amount of moisture in the PE-CVD TMS SiO₂film 42 a is increased merely by +0.2 to 0.3 wt % and thus the amount ofmoisture is seldom varied.

[0105] As described above, it is found that both the structural water(the moisture contained in the film due to the film forming gas and thefilm structure immediately after the film formation) and the physicaladsorption water (the incoming moisture that is adsorbed and absorbedphysically) in the PE-CVD TMS SiO₂ film 42 a are small in contrast tothe PE-CVD TEOS SiO₂ film 51 a.

[0106] (v) FT-IR Absorption Intensity

[0107] Then, examined results of the infrared rays absorption intensityin the sample S1 by the FT-IR analysis method (Fourier TransformInfrared analysis method) are shown in FIG. 5A. Similarly, examinedresults in the comparative samples CS1, CS2 are shown in FIG. 5B.

[0108] An ordinate of FIG. 5A denotes the absorption intensity expressedin a linear scale (arbitrary unit), and an abscissa denotes the wavenumber expressed in a linear scale (cm⁻¹). Similarly, this is true ofFIG. 5B.

[0109] As shown in FIG. 5A, the peak of the infrared rays absorptionintensity having a center wave number in a range of 2270 to 2350 cm⁻¹ isconfirmed. In contrast, as shown in FIG. 5B, such peak is not watched inthe comparative samples CS1, CS2.

[0110] (vi) Water Resistance

[0111] The water resistance of the PE-CVD TMS SiO₂ film 42 b is exampledby the high pressure humidifying test (pressure-cooker test) while usingthe samples S2, S3 shown in FIG. 2B. By way of comparison, the similarexamination is applied to the comparative sample CS3 employing thePE-CVD TEOS SiO₂ film 51 b in place of the PE-CVD TMS SiO₂ film 42 b andthe comparative sample CS5 employing the PE-CVD SiN film 53 similarly.

[0112] The conditions of the high pressure humidifying test are given asfollows. The leaving time is used as a parameter.

[0113] Temperature: 121° C.

[0114] Pressure: 2.0 atm

[0115] Humidity: 100% R.T. (Room Temperature)

[0116] Evaluation of the water resistance is carried out by evaluatingan amount of P═O bonds contained in the examined insulating film afterthe high pressure humidifying test. In order to evaluate the amount ofP═O bonds contained in the BPSG film 43, the P═O absorption coefficientis measured by the FT-IR analysis method. If the moisture enters theBPSG film 43, the P═O bonds in the film react with the moisture todestroy. In this case, if the PE-CVD TMS SiO₂ film 42 b for covering theBPSG film 43 has the high water resistance, the moisture does not passthrough such film and thus the P═O bonds in the BPSG film 43 are neverdestroyed. As a result, it is possible to say that, if the timedependent change of the P═O absorption coefficient becomes smaller, thewater resistance becomes higher.

[0117]FIG. 6 is a graph showing the time dependent change of an amountof contained phosphorus in the insulating film after the high pressurehumidifying test is carried out. An ordinate denotes the P═O absorptioncoefficient (arbitrary unit) expressed in a linear scale, and anabscissa denotes the leaving time (H (hour)) expressed in a linearscale.

[0118] Based on the results shown in FIG. 6, it is found that, evenafter both the samples S2, S3 are left for 150 hours as they are, theirP═O absorption coefficients are seldom changed from the initial P═Oabsorption coefficient regardless of the magnitude of the thickness ofthe PE-CVD TMS SiO₂ film 42 b, like the PE-CVD SiN film 53 in thecomparative sample CS5, i.e., the PE-CVD TMS SiO₂ film 42 b has thewater resistance equivalent to the PE-CVD SiN film 53.

[0119] Also, the water resistance is examined by another high pressurehumidifying test while using the examined sample S3 and the comparativesamples CS3, CS4.

[0120] The conditions of the high pressure humidifying test are the sameas above.

[0121] The results are shown in FIG. 7. An ordinate of FIG. 7 denotesthe water resistance (%) expressed in a linear scale, and an abscissadenotes the leaving time (H (hour)) expressed in a linear scale. Thesample S3 and the comparative samples CS3, CS4 are used as a parameter.

[0122] Like the above, the evaluation of the water resistance is carriedout by evaluating an amount of P═O bonds contained in the examinedinsulating film after the high pressure humidifying test. The waterresistance in FIG. 7 is derived by calculating the P═O absorptioncoefficient obtained after the high pressure humidifying test on thebasis of the P═O absorption coefficient before the leaving-off, that isassumed as 100.

[0123] As shown in FIG. 7, it is found that the sample S3 has the waterresistance of 97.4% (100 H), that exceeds the comparative samples CS3,CS4.

[0124] (vii) Leakage current of the film

[0125] The examined sample S1A shown in FIG. 2E is formed. That is, theelectrode 45 is formed on the PE-CVD TMS SiO₂ film 42 having a filmthickness (t) of 200 nm in the sample S1 according to the presentinvention.

[0126] The leakage current flowing through the silicon substrate 41 andthe electrode 45 is measured by applying the voltage between the siliconsubstrate 41 and the electrode 45. The silicon substrate 41 is grounded,and the negative voltage is applied to the electrode 45.

[0127] According to the results, the leakage current of the PE-CVD TMSSiO₂ film 42 a as the single substance is on the order of 10⁻⁸ A/cm² atthe electric field strength of 5 MV/cm, and the breakdown voltage isabout 10 MV/cm in terms of the electric field.

[0128] (viii) Adhesiveness of the film

[0129] The adhesiveness between the PE-CVD TMS SiO₂ film 42 c accordingto the present invention and the underlying low dielectric constantinsulating film 44 a, 44 b is examined employing the samples S4, S5.Also, the sample which is subjected to the surface treatment prior tothe film formation and the sample which is not subjected to the surfacetreatment are prepared, and then the similar examination is carried out.The surface treatment executed prior to the film formation is thetreatment for reforming the surface of the processed film by employingthe plasma of N₂, NH₃, H₂, etc.

[0130] By way of comparison, the PE-CVD TEOS SiO₂ film 51 c is employedin place of the PE-CVD TMS SiO₂ film 42 c, and similar examinations arecarried out employing the inorganic coating insulating film 44 a (thecomparative sample CS6) and the organic coating insulating film 44 b(the comparative sample CS7)as the low dielectric constant insulatingfilm.

[0131] As the test for examining the adhesiveness of the film, the peeltest by using the tape and the peel test by the CMP (Chemical MechanicalPolishing) on the entire surface of the wafer are carried out.

[0132] According to the examined results, regardless of the presence ofthe surface treatment prior to the film formation, the PE-CVD TMS SiO₂film 42 c has the good adhesiveness to the inorganic coating insulatingfilm 44 a and the organic coating insulating film 44 b. In contrast, adegree of the adhesiveness of the PE-CVD TEOS SiO₂ film 51 c is inferiorto the PE-CVD TMS SiO₂ film 42 c as a whole. Then, difference in theadhesiveness appeared in response to whether or not the surfacetreatment is applied prior to the film formation. That is, the samplewhich is subjected to the surface treatment prior to the film formationhad the higher adhesiveness than the sample which is not subjected tothe surface treatment.

[0133] (ix) Defect Generating Rate due to Heat Cycle

[0134] The defect generating rate due to the heat cycle about the sampleS6 and the comparative samples CS8, CS9 is examined. Respective samplesare sealed in the package. Test conditions of the heat cycle are givenas follows. The cycle number is used as a parameter.

[0135] High temperature (holding time): 150° C. (20 minutes)

[0136] Low temperature (holding time): −55° C. (20 minutes)

[0137] Cycle number: 100, 200, 300, 500° C.

[0138] The defect is defined as the sample in which a peeling-off of afilm or a crack of a film has generated. The results are shown in FIG.9. An ordinate of FIG. 9 denotes the defect generating rate (%)expressed in a linear scale, and an abscissa denotes the types of thesample. The types of the sample are the sample S6, and the comparativesamples CS8, CS9, as explained above, in order from the left side. Thepartition area indicated by a bar graph denotes a fraction defective ata particular cycle number, the partition area hatched by lateral linesdenotes the fraction defective at 100° C., the partition area hatched byvertical lines denotes the fraction defective at 200° C., the partitionarea hatched by oblique lines denotes the fraction defective at 300° C.,and the white partition area on a black ground denotes the fractiondefective at 500° C.

[0139] As shown in FIG. 9, in the sample S6 employing the silicon oxidefilm of the present invention as both the upper protection layer and thelower protection layer, the defect is generated at 300° C. or more, butthe defect generating rate is about 2 to 3% even if the defectgenerating rates at 300° C. and 500° C. are added. In the comparativesample CS8 employing the silicon oxide film 52 d of the presentinvention only as the lower protection layer out of the upper protectionlayer and the lower protection layer, the defect is generated almostuniformly from 100° C. to 500° C., and the defect generating rate isabout 25% in total. In the comparative sample CS9 not employing thesilicon oxide film 42 d, 42 e of the present invention as both the upperprotection layer and the lower protection layer, the defect is generatedfrom 100° C. to 500° C. In particular, the defect generating rate at300° C. and 500° C. are increased, and the defect generating rate isabout 53% in total.

[0140] (x) Examination of the barrier characteristic to the copper (Cu)

[0141] (a) TDDB (Time Dependent Dielectric Breakdown) test

[0142] The TDDB test measures a time required to come up to thedielectric breakdown when the voltage is applied to the sample.

[0143] The examined sample is prepared by stacking the PE-CVD TMS SiO₂film according to the present invention and the Cu film on the Sisubstrate in sequence. By way of comparison, the similar examination isapplied to the sample employing the PE-CVD TEOS SiO₂ film in place ofthe PE-CVD TMS SiO₂ film, and the sample interposing the TiN filmbetween the Cu film and the PE-CVD TEOS SiO₂ film.

[0144] According to the examined results, the breakdown lifetime of10×10⁵ seconds is obtained at the electric field strength of 8 MV/cm.

[0145] In contrast, in the sample employing the PE-CVD TEOS SiO₂ film,the electric field strength is 8 MV/cm to get the breakdown lifetime onthe order of 10×10⁵ seconds. This means that the breakdown lifetime ofthe sample employing the PE-CVD TMS SiO₂ film is longer by almost sixfigures than the sample employing the PE-CVD TEOS SiO₂ film.

[0146] In the sample interposing the TiN film between the Cu film andthe PE-CVD TEOS SiO₂ film, the electric field strength is 7.5 MV/cm toget the breakdown lifetime on the order of 10×10⁵ seconds.

[0147] With the above, it is possible to say that the sample employingthe PE-CVD TMS SiO₂ film has the longer breakdown lifetime by almost sixfigures than the sample employing the PE-CVD TEOS SiO₂ film and has thebarrier characteristic to Cu, that is equivalent to or more than the TiNfilm.

[0148] (b) Examination of heat resistance

[0149] As shown in FIG. 10, the examined sample is prepared by stackingthe PE-CVD TMS SiO₂ film of 125 nm thickness according to the presentinvention and the Cu film on the Si substrate (not shown) to contact toeach other.

[0150] The examination is made by measuring the Cu concentrationdistribution state in the PE-CVD TMS SiO₂ film on the basis of the stateobtained immediately after the film formation (indicated by a dottedline in FIG. 10) after the sample is processed for a predetermined time(three types, i.e., 1 hour (chain double-dashed line), 7 hours (solidline), and 15 hours (dot-dash line)) at the temperature of 470° C.

[0151]FIG. 10 is a graph showing the examined results. In FIG. 10, anordinate on the left side denotes a Cu concentration and a Siconcentration (cm⁻³) represented in a logarithmic scale. An abscissadenotes a depth (nm) measured from one surface of the PE-CVD TMS SiO₂film toward the Cu film side and represented in a linear scale.

[0152] As shown in FIG. 10, the distribution is seldom changed from thedistribution obtained immediately after the film formation. In otherwords, it is found that the PE-CVD TMS SiO₂ film has the sufficientbarrier characteristic to the Cu.

[0153] In the above, the alkoxy compound (ex. TMS) having Si—H bonds isemployed as the silicon-containing gas in the film forming gas. But thesiloxane having Si—H bonds may be employed.

[0154] Also, N₂O is employed as the oxygen-containing gas in the above.But any one selected from the group consisting of oxygen (O₂), nitrogendioxide (NO₂), carbon monoxide (CO), carbon dioxide (CO₂) and water(H₂O) may be employed.

[0155] In addition, if any one selected from the group consisting ofhydrogen (H₂) and nitrogen (N₂) is added to the above film forming gas,the density can be further enhanced.

[0156] (Third Embodiment)

[0157] Next, a semiconductor device and a method of manufacturing thesame according to a third embodiment of the present invention will beexplained with reference to FIGS. 11A and 11E hereunder.

[0158]FIGS. 11E are sectional views showing the semiconductor deviceaccording to the third embodiment of the present invention.

[0159] A base protection layer 23 consisting of a silicon-containinginsulating film according to the present invention is formed on a basesubstrate 22. Three-layered wirings 24, 29, 34 which interpose aninterlayer insulating film between any two adjacent wirings are formedon the base protection layer 23. These interlayer insulating films areconstructed by a lower protection layer 25, 30, a main insulating film26, 31, and an upper protection layer 27, 32. The lower protection layer25, 30 and upper protection layer 27, 32 are made of thesilicon-containing insulating film according to the present invention. Aprotection layer 35 made of the silicon-containing insulating filmaccording to the present invention and a coating insulating film 36 areformed on the uppermost wiring 34.

[0160] The silicon-containing insulating film according to the presentinvention, which constitutes the protection layer 23, 25, 27, 30, 32,35, has a peak of the absorption intensity of the infrared rays in arange of the wave number 2270 to 2350 cm⁻¹, a film density in a range of2.25 to 2.40 g/cm³, and a relative dielectric constant in a range of 3.3to 4.3.

[0161] A silicon substrate or a base substrate in which a wiring or aninsulating film is formed on a silicon substrate is employed as the basesubstrate 22.

[0162] According to the experiment carried out by the inventor of thepresent application, the silicon-containing insulating film 23, 25, 27,30, 32, 35 having aforementioned characteristics has a high mechanicalstrength, is dense, is excellent in the water resistance, is little in amoisture content in the film similar to the silicon nitride film, and islower in the relative dielectric constant in contrast to the siliconnitride film. Further, the silicon-containing insulating film 23, 25,27, 30, 32, 35 has a good adhesiveness with the coating insulating film.

[0163] Accordingly, an employment of the silicon-containing insulatingfilm having aforementioned characteristics as the protection layer 23,25, 27, 30, 32, 35 for covering the wiring 24, 29, 34, etc, contributesto a prevention of a corrosion of the wirings 24, 29, 34 throughblocking a penetration of incoming water as well as a reduction of aparasitic capacitance between the wirings 24, 29, 34.

[0164] Moreover, an employment of the silicon-containing insulating filmhaving aforementioned characteristics as the protection layer 23, 25,27, 30, 32, 35 for protecting an upper and a lower surfaces of thecoating insulating film 26, 31, 36 contributes to a prevention of acorrosion of the wirings 24, 29, 34 through blocking a flowing-out ofmoisture to outer periphery of the protection layer 23, 25, 27, 30, 32,35 and a penetration of incoming water as well as a reduction of aparasitic capacitance between the wirings 24, 29, 34.

[0165] Further, since the silicon-containing insulating film havingaforementioned characteristics has a good adhesiveness to the coatinginsulating film 26, 31, 36 and a high mechanical strength, the laminatedstructure is prevented from a destroy such as a peeling-off of thefilms, etc., even if a mechanical shock is applied to the laminatedstructure from outside.

[0166]FIGS. 11A and 11E are sectional views showing the method ofmanufacturing the semiconductor device according to the third embodimentof the present invention. TMS+N₂O is employed as the film forming gasfor the base protection layer, the lower protection layer, the upperprotection layer, and the protection layer, which are formed on at leastany surface of the upper and lower surfaces of the coating insulatingfilm and to which the present invention is applied.

[0167] First, as shown in FIG. 11A, a base insulating film 23 made ofthe PE-CVD TMS SiO₂ film is formed on the silicon substrate (basesubstrate) 22 by the plasma CVD method using TMS+N₂O as the film forminggas.

[0168] In order to form the PE-CVD TMS SiO₂ film (base protection layer)23, first the silicon substrate 22 is loaded into the chamber 1 of theplasma film forming apparatus 101 shown in FIG. 1 and then held by thesubstrate holder 3. Then, the silicon substrate 22 is heated to be heldat the temperature of 350° C. TMS and N₂O gas are introduced into thechamber 1 of the plasma film forming apparatus 101 at flow rates of 100sccm and 3000 sccm respectively to hold the pressure at 0.7 Torr. Then,the power 0.3 W/cm² having the frequency of 380 kHz is applied to thelower electrode 3 and also the power 0.3 W/cm² having the frequency of13.56 MHz is applied to the upper electrode 2.

[0169] Accordingly, TMS and N₂O are plasmanized. The PE-CVD TMS SiO₂film 23 of about 200 nm thickness is formed while holding this conditionfor a predetermined time. According to the examination, the formedPE-CVD TMS SiO₂ film 23 has the relative dielectric constant of about3.9 that is measured at the frequency of 1 MHz, and the leakage currentof 10⁻⁸ A/cm² at the electric field strength of 5 MV/cm.

[0170] Then, a first wiring 24 is formed on the base protection layer23. Then, a first barrier insulating film (a lower protection layer) 25made of the PE-CVD TMS SiO₂ film having the thickness of about 500 nm isformed thereon by the plasma CVD method that is set to the same filmforming conditions used when the above PE-CVD TMS SiO₂ film 23 isformed.

[0171] The formed first barrier insulating film 25 has the relativedielectric constant of about 3.9 that is measured at the frequency of 1MHz, and the leakage current of 10⁻⁸ A/cm² at the electric fieldstrength of 5 MV/cm.

[0172] In this case, if the first wiring 24 is formed of the copperwiring, a TaN film serving as the copper barrier to the base protectionlayer 23 and a Cu film formed by the sputter, although not shown, areformed between the base protection layer 23 and the first wiring 24 fromthe bottom.

[0173] Then, as shown in FIG. 11B, a first coating insulating film 26having the low relative dielectric constant and the film thickness ofabout 500 to 1000 nm is formed by the spin coating method employing thecoating liquid containing the silicon-containing inorganic compound orthe silicon-containing organic compound. The first coating insulatingfilm 26 constitutes a main insulating film. These elements constitutethe substrate 20.

[0174] Where the coating liquid containing the silicon-containinginorganic compound is the coating liquid used to form the inorganiccoating insulating film, explained in the above (Formation of Samples)item in the second embodiment, and contains the silicon. Similarly, thecoating liquid containing the silicon-containing organic compound is thecoating liquid used to form the organic coating insulating film andcontains the silicon.

[0175] Then, as shown in GIG.11C, a second barrier insulating film (anupper protection layer) 27 made of the PE-CVD TMS SiO₂ film having thethickness of about 50 nm is formed on the first coating insulating film26 by the plasma CVD method that is set to the same film formingconditions used for the formation of the above PE-CVD TMS SiO₂ film 23.

[0176] Then, a photoresist film (not shown) is formed on the secondbarrier insulating film 27. Then, as shown in FIG. 11D, an openingportion in the photoresist film is formed in the via-hole forming areaby patterning the photoresist film. Then, first the second barrierinsulating film 27 is etched and removed via the opening portion in thephotoresist film by the reactive ion etching (RIE) using the plasmanizedCF₄+CHF₃-based mixed gas. Then, the first coating insulating film 26 isetched and removed by using the CF₄+CHF₃-based mixed gas, whosecomposition ratio is changed from the gas used in the etching of thesecond barrier insulating film 27. Accordingly, an opening portion isformed to expose the first barrier insulating film 25 at the bottom ofthe opening portion. A concentration of the CF₄+CHF₃-based mixed gas maybe adjusted by adding Ar+O₂, etc. in addition to CF₄+CHF₃.

[0177] After this, the ashing of the photoresist film is carried out.

[0178] Then, the first barrier insulating film 25 is etched and removedvia the opening portion in the second barrier insulating film 27 and theopening portion in the first coating insulating film 26 by the reactiveion etching (RIE) using the plasmanized CF₄+CHF₃-based mixed gas, thathas the same composition ratio as the gas used in the etching of theabove second barrier insulating film 27. Accordingly, a first via holeis formed to expose the first wiring 24 from its bottom portion. At thistime, the first wiring 24 has the etching resistance against the etchinggas for the above barrier insulating film 25. As a result, the firstwiring 24 is not badly affected by the etching gas. In this case, if asurface of the first wiring 24 is oxidized, an oxide film may be removedby exposing to the hydrogen plasma diluted with a reducing gas, forexample, NH₃, an inert gas such as argon, nitrogen, or the like afterthe ashing step of the photoresist film and the etching step of thefirst barrier insulating film 25 are completed.

[0179] Then, the photoresist film is removed, and then a conductive filmis filled in the first via hole 28. Then, a second wiring 29 made ofcopper or aluminum is formed to be connected to the first wiring 24 viathe conductive film. In this case, if the second wiring 29 is mademainly of copper, an underlying conductive film consisting of a barriermetal film such as tantalum nitride (TaN), etc. and a copper film formedby the sputter method is provided in the via hole 28 and on the secondbarrier insulating film 27, and then a conductive film made of copper isdeposited thereon.

[0180] Then, a third barrier insulating film (a lower protection layer)30 made of the PE-CVD TMS SiO₂ film having the film thickness of about50 nm; a second coating insulating film 31 having the low dielectricconstant and the film thickness of about 500 to 1000 nm, that is formedon the third barrier insulating film 30 by the same material andconditions as the coating method in FIG. 11B; and a fourth barrierinsulating film (an upper protection layer) 32 made of the PE-CVD TMSSiO₂ film having the film thickness of about 50 nm are formed insequence by repeating the steps shown in FIGS. 11A to 11D. Then, asecond via hole 33 is formed to pierce the fourth barrier insulatingfilm 32, the second coating insulating film 31, and the third barrierinsulating film 30. Then, a third wiring 34 that is connected to thesecond wiring 29 via the second via hole 33 is formed on the fourthbarrier insulating film 32.

[0181] Then, a fifth barrier insulating film (a lower protection layer)35 made of the PE-CVD TMS SiO₂ film having the film thickness of about50 nm is formed by the plasma CVD method of the present invention tocover the third wiring 34. Then, a third coating insulating film 36having the low dielectric constant and the film thickness of about 500to 1000 nm is formed on the fifth barrier insulating film 35 by the samematerial and conditions as the coating method in FIG. 11B.

[0182] With the above, the formation of the second wiring 29 that isconnected to the first wiring 24 and the third wiring 34 that isconnected to the second wiring 29 is completed.

[0183] According to the third embodiment, the upper and lower surfacesof the first coating insulating film 26 having the low dielectricconstant are covered with the first barrier insulating film 25 made ofthe PE-CVD TMS SiO₂ film and the second barrier insulating film 27 madeof the PE-CVD TMS SiO₂ film. Similarly, the upper and lower surfaces ofthe second coating insulating film 31 having the low dielectric constantare covered with the third barrier insulating film 30 made of the PE-CVDTMS SiO₂ film and the fourth barrier insulating film 32 made of thePE-CVD TMS SiO₂ film.

[0184] By the way, as indicated by the examined results in the secondembodiment, the PE-CVD TMS SiO₂ film to which the present invention isapplied has the qualities such that such film is dense, is excellent inthe water resistance, and has the small amount of contained moisture inthe film, that are equivalent to the silicon nitride film.

[0185] Accordingly, the entering of the incoming moisture into the firstcoating insulating film 26 and the second coating insulating film 31 canbe blocked. Also, if the moisture is contained originally in the firstcoating insulating film 26 and the second coating insulating film 31,such moisture can be prevented from flowing out to the peripheralportions of the first coating insulating film 26 and the second coatinginsulating film 31. Therefore, variation in the relative dielectricconstant due to the amount of moisture contained in the first coatinginsulating film 26 and the second coating insulating film 31 can besuppressed.

[0186] Further, the PE-CVD TMS SiO₂ film has the equivalent quality tothe silicon nitride film in the respect of density, but has the qualityof the small relative dielectric constant, that is largely differentfrom the silicon nitride film. As a result, if the PE-CVD TMS SiO₂ filmis employed as the interlayer insulating film, the smaller relativedielectric constant of the interlayer insulating film can be achieved.

[0187] In particular, if the PE-CVD TMS SiO₂ film is employed as thefirst barrier insulating film 25 and the second barrier insulating film27 that protect the lower and upper surfaces of the first coatinginsulating film 26 respectively, the smaller relative dielectricconstant can be achieved as the overall first interlayer insulating filmthat is constructed by these films. Similarly, the PE-CVD TMS SiO₂ filmis employed as the third barrier insulating film 30 and the fourthbarrier insulating film 32 that protect the lower and upper surfaces ofthe second coating insulating film 31, the smaller relative dielectricconstant can be achieved as the overall second interlayer insulatingfilm that is constructed by these films.

[0188] Moreover, the peripheral portions of the first wiring 24, thesecond wiring 29, and the third wiring 34 are wrapped by the baseinsulating film 23 and the first barrier insulating film 25, the secondbarrier insulating film 27 and the third barrier insulating film 30, andthe fourth barrier insulating film 32 and the fifth barrier insulatingfilm 35 respectively. Therefore, the corrosion of the first wiring 24,the second wiring 29, and the third wiring 34 can be prevented byblocking the enter of the incoming moisture.

[0189] Particularly, since the base insulating film 23 is also formed ofthe PE-CVD TMS SiO₂ film to which the present invention is applied, allperipheral portions of the first wiring 24 are protected by the PE-CVDTMS SiO₂ film. Therefore, the corrosion of the first wiring 24 can beprevented more completely by blocking the permeation of the moisturefrom all peripheral portions.

[0190] In the above third embodiment, the PE-CVD TMS SiO₂ film formed bythe plasma enhanced CVD method according to the present invention isemployed as the base protection layer 23. However, a thermal oxide filmformed by oxidizing the silicon substrate 22 by heating it in theoxygen-containing atmosphere may be employed as the base insulating film23. Further, an NSG film or a BPSG (BoroPhosphoSilicate Glass) film,etc. which is formed by the CVD method using the organicsilicon-containing gas may be employed as the base insulating film 23.

[0191] (Fourth Embodiment)

[0192] Next, a semiconductor device and a method of manufacturing thesame according to a fourth embodiment of the present invention will beexplained with reference to FIGS. 12A and 12E hereunder.

[0193]FIGS. 12D is a sectional view showing a semiconductor deviceaccording to a fourth embodiment of the present invention.

[0194] A difference from the third embodiment resides in that sidewallsin the first via hole 28 and the second via hole 33 are covered with thePE-CVD TMS SiO₂ films 37, 38 to which the present invention is appliedand thus the first coating insulating film 26 and the second coatinginsulating film 31 are not exposed in the first via hole 28 and thesecond via hole 33.

[0195] Next, the method for implementing the above structure isexplained. FIGS. 12A to 12D are sectional views showing a method ofmanufacturing the semiconductor device according to a fourth embodimentof the present invention. TMS+N₂O is used as the film forming gasapplied to the formation of a sidewall protection layer other than thelower and upper protection layers, to which the present invention isapplied.

[0196] In order to implement the above structure, as shown in FIG. 12A,the first via hole 28 is formed after the step shown in FIG. 11C. Then,as shown in FIG. 12B, the PE-CVD TMS SiO₂ film 37 a having the filmthickness of about 50 nm, to which the present invention is applied, isformed on the second barrier insulating film 27 so as to cover the firstvia hole 28. Then, as shown in FIG. 12C, the PE-CVD TMS SiO₂ film 37 ais etched by the anisotropic etching to leave the PE-CVD TMS SiO₂ film(a sidewall protection layer) 37 on the sidewall of the first via hole28.

[0197] Then, as shown in FIG. 12D, the second wiring 29 made of copperor aluminum is formed to be connected to the first wiring 24 via theconductive film. Then, the interlayer insulating film consisting of thesecond coating insulating film 31 and the third and fourth barrierinsulating films 30, 32, that are formed to cover a lower and an uppersurfaces of the second coating insulating film 31 and to have the filmthickness of about 50 nm; the second via hole 33 to pierce theinterlayer insulating film; a sixth barrier insulating film 38 made ofthe PE-CVD TMS SiO₂ film having the film thickness of about 50 nm tocover the sidewall of the second via hole 33; the third wiring 34connected to the second wiring 29 via the second via hole 33; the fifthbarrier insulating film 35 made of the PE-CVD TMS SiO₂ film having thefilm thickness of about 50 nm to cover the third wiring 34; and thethird coating insulating film 36 are formed by repeating the abovesteps.

[0198] According to the fourth embodiment, the first coating insulatingfilm 26 and the second coating insulating film 31 including the insidesof the first via hole 28 and the second via hole 33 are completelyprotected by the PE-CVD TMS SiO₂ films 25, 27, 37 and 30, 23, 38.Therefore, both the entering of the moisture into the first coatinginsulating film 26 and the second coating insulating film 31 and theflowing-out of the moisture from the first coating insulating film 26and the second coating insulating film 31 to the peripheral portions canbe blocked more completely.

[0199] As a result, the time dependent change in the relative dielectricconstant of the interlayer insulating film and the corrosion of theupper and lower wirings 24, 29, 34 under and on the interlayerinsulating film can be prevented.

[0200] (Fifth Embodiment)

[0201]FIG. 13 is a sectional view showing a semiconductor device and amethod of manufacturing the same according to a fifth embodiment of thepresent invention.

[0202] This semiconductor device has a configuration in which four setsof laminated structures are laminated. The laminated structure of oneset comprises a set of a protection layer, a wiring group on theprotection layer and an interlayer insulating film or a cover insulatingfilm covering a wiring group.

[0203] In other words, this semiconductor device has a first wiringgroup of wirings 63 a to 63 d, a second wiring group of wirings 66 a to66 c, a third wiring group of wirings 69 a to 69 d, and a fourth wiringgroup of wirings 72 a to 72 d on first to fourth protection layers 62,65, 68, 71 made of the PE-CVD SiO₂ film according to the presentinvention, respectively. The symbols indicating the wiring groups areoccasionally omitted in the following description in order to simplifythe explanation.

[0204] The respective wiring groups are covered with interlayerinsulating films 64, 67, 70 made of a coating insulating film and acover insulating film 73 made of a coating insulating film in order fromthe bottom first wiring group of wirings 63a to 63d.

[0205] The PE-CVD SiO₂ film constituting each of the first to fourthprotection layers 62, 65, 68, 71 has a peak of the absorption intensityof the infrared rays in a range of the wave number 2270 to 2350 cm⁻¹, afilm density in a range of 2.25 to 2.40 g/cm³, and a relative dielectricconstant in a range of 3.3 to 4.3.

[0206] As described above, according to the fifth embodiment, theprotection layers 65, 68, 71 according to the present invention are putbetween any adjacent two wiring groups.

[0207] The protection layers 65, 68, 71 themselves are dense, and areexcellent in the water resistance. From the characteristics, they have afunction of blocking a penetration of incoming moisture and a pass ofleakage current. Accordingly, the semiconductor device according to afifth embodiment can prevent the wirings from corrosion, and cansuppress leakage current between the wiring groups.

[0208] Further, the protection layers 65, 68, 71 are formed to contactthe interlayer insulating film 64, 67, 70 and the cover insulating film73. Since the PE-CVD SiO₂ film constituting each of the protectionlayers 62, 65, 68, 71 has a good adhesiveness to the coating insulatingfilm constituting each of the interlayer insulating film 64, 67, 70 andthe cover insulating film 73, the semiconductor device according to afifth embodiment can prevent the films from peeling-off.

[0209] Further, since the coating insulating films are employed as theinterlayer insulating film 64, 67, 70 and the cover insulating film 73,the interlayer insulating film 64, 67, 70 and the cover insulating film73 which are excellent in flatness can be obtained.

[0210] The manufacturing method will be explained hereunder.

[0211] As shown in FIG. 13, first the first protection layer (the firstbarrier insulating film) 62 made of the PE-CVD TMS SiO₂ film having thefilm thickness of 200 nm, to which the present invention is applied, isformed on the substrate 61. In this case, the semiconductor substrateitself or the structure obtained by forming the base insulating film andthe wiring on the semiconductor substrate may be employed as thesubstrate 61.

[0212] Then, the first wiring group of wirings 63 a to 63 d are formedon the first protection layer 62. Then, the first coating insulatingfilm 64 is formed by covering the first wiring group of wirings 63 a to63 d with the same material as the third and fourth embodiments and byemploying the same film forming method as them.

[0213] Then, the second protection layer (the second barrier insulatingfilm) 65 made of the second PE-CVD TMS SiO₂ film having a film thicknessof about 50 nm, to which the present invention is applied, is formed onthe first coating insulating film 64. Then, the second wiring group ofsecond wirings 66 a to 66 c are formed on the second protection layer65. Then, the second coating insulating film 67 is formed by coveringthe second wiring group of wirings 66 a to 66 c with the same materialas the third and fourth embodiments and by employing the same filmforming method as them.

[0214] Then, the third protection layer (the third barrier insulatingfilm) 68 having a film thickness of about 50 nm and made of the PE-CVDTMS SiO₂ film; the third wiring group of wirings 69 a to 69 d; the thirdcoating insulating film 70; the fourth protection layer (the fourthbarrier insulating film) 71 having a film thickness of about 50 nm andmade of the PE-CVD TMS SiO₂ film; the fourth wiring group of wirings 72a to 72 c; and the fourth coating insulating film 73 are formed insequence on the second coating insulating film 67, by repeating twicesequentially the step of forming the above PE-CVD TMS SiO₂ film, thestep of forming the wiring, and the step of forming the coatinginsulating film.

[0215] Accordingly, there can be formed a semiconductor integratedcircuit device including the multi-layered, e.g., four-layered in total,wiring groups 63 a to 63 d, 66 a to 66 c, 69 a to 69 d, 72 a to 72 c,that are insulated and separated by the coating insulating films 64, 67,70 and the protection layers 65, 68, 71.

[0216] As described above, according to the fifth embodiment, theprotection layers 65, 68, 71 are interposed between the wiring groups 63a to 63 d, 66 a to 66 c, 69 a to 69 d, 72 a to 72 c.

[0217] That is, since the coating insulating films 64, 67, 70 areemployed as the main interlayer insulating film, the interlayerinsulating film that is excellent in the flatness can be obtained.

[0218] Also, the protection layers 65, 68, 71 per se are dense and havethe water resistance, they have functions of preventing the permeationof the incoming moisture and preventing the flow of the leakage current.Therefore, the corrosion of the wiring groups 63 a to 63 d, 66 a to 66c, 69 a to 69 d, 72 a to 72 c due to the incoming moisture can beprevented, and also the leakage current between the wiring groups 63 ato 63 d, 66 a to 66 c, 69 a to 69 d, 72 a to 72 c can be suppressed.

[0219] With the above, the present invention is explained in detailbased on the embodiments, but the scope of the present invention is notlimited to examples given concretely in the above embodiments.Variations of the above embodiments may be contained in the scope of thepresent invention without departing from the gist of the presentinvention.

[0220] As described above, according to the present invention, after thecoating insulating film is formed on the substrate, the protection layermade of the silicon-containing insulating film for covering the coatinginsulating film is formed by plasmanizing the film forming gas, thatconsists of the alkoxy compound having Si—H bonds or the siloxane havingSi—H bonds and any one oxygen-containing gas out of O₂, N₂O, NO₂, CO,CO₂, and H₂O, to react.

[0221] The silicon-containing insulating film of the present inventionconstituting the protection layer has a peak of the absorption intensityof the infrared rays in a range of the wave number 2270 to 2350 cm⁻³, afilm density in a range of 2.25 to 2.40 g/cm³, and a relative dielectricconstant in a range of 3.3 to 4.3.

[0222] The protection layer formed in this manner to have the abovecharacteristics has the good adhesiveness to the coating insulatingfilm, is dense to the same extent as the silicon nitride film, isexcellent in the water resistance, and contains the small amount ofcontained moisture in the film. Therefore, if the coating insulatingfilm and the protection layer for coating the coating insulating filmare formed, there can be obtained the interlayer insulating film thatcan have the more complete barrier characteristic to the entering of themoisture into the coating insulating film from the outside and theflowing-out of the moisture to the outside, and is excellent inflatness.

[0223] Also, the above protection layer has the smaller relativedielectric constant than the silicon nitride film in addition to theabove characteristics. Therefore, if the barrier insulating filmaccording to the present invention are formed to cover the lower andupper surfaces of the coating insulating film serving as the maininterlayer insulating film between the wiring layers, there can beobtained the interlayer insulating film that has more completely thebarrier characteristic to the entering/flowing-out of the moistureinto/from the coating insulating film, the barrier characteristic to theleakage current, etc. and also achieves the low dielectric constant as awhole.

[0224] The silicon-containing insulating film having aforementionedcharacteristics has a good adhesiveness with the coating insulatingfilm, and has the high mechanical strength. Therefore, the laminatedstructure can be prevented from a destroy such as a peeling-off of thefilms, etc., even if a mechanical shock is applied to the laminatedstructure from outside.

What is claimed is:
 1. A semiconductor device manufacturing methodcomprising the steps of: preparing a substrate on a surface of which acoating insulating film is formed by coating a coating liquid containingany one selected from a group consisting of silicon-containing inorganiccompound and silicon-containing organic compound; and forming aprotection layer for covering the coating insulating film byplasmanizing a first film forming gas to react, wherein the first filmforming gas includes any one selected from a group consisting of alkoxycompound having Si—H bonds and siloxane having Si—H bonds and any oneoxygen-containing gas selected from a group consisting of O₂, N₂O, NO₂,CO, CO₂, and H₂O.
 2. A semiconductor device manufacturing methodaccording to claim 1, wherein the first film forming gas furtherincludes any one selected from a group consisting of N₂ and H₂.
 3. Asemiconductor device manufacturing method according to claim 1, whereinthe alkoxy compound having Si—H bonds constituting the first filmforming gas is formed of trimethoxysilane (TMS:SiH(OCH₃)₃).
 4. Asemiconductor device manufacturing method according to claim 1, whereinthe siloxane having Si—H bonds constituting the first film forming gasis formed of tetramethyldisiloxane (TMDSO:(CH₃)₂HSi—O—SiH(CH₃)₂).
 5. Asemiconductor device manufacturing method according to claim 1, whereina first electrode and a second electrode of a parallel-plate type areprovided as means for plasmanizing the film forming gas, and, when afilm is formed, a high frequency power having a frequency of 1 MHz ormore is applied to the first electrode and a low frequency power havinga frequency of 100 kHz to 1 MHz is applied to the second electrode whichthe substrate is loaded.
 6. A semiconductor device manufacturing methodaccording to claim 1, wherein the substrate has a first wiring, and aprotection layer for covering the first wiring, that is formed byplasmanizing a second film forming gas to react, wherein the second filmforming gas includes any one selected from a group consisting of alkoxycompound having Si—H bonds and siloxane having Si—H bonds and any oneoxygen-containing gas selected from a group consisting of O₂, N₂O, NO₂,CO, CO₂, and H₂O.
 7. A semiconductor device manufacturing methodaccording to claim 6, wherein the second film forming gas includes anyone selected from a group consisting of N₂ and H₂.
 8. A semiconductordevice manufacturing method according to claim 6, wherein the alkoxycompound having Si—H bonds constituting the second film forming gas isformed of trimethoxysilane (TMS:SiH(OCH₃)₃).
 9. A semiconductor devicemanufacturing method according to claim 6, wherein the siloxane havingSi—H bonds constituting the second film forming gas is formed oftetramethyldisiloxane (TMDSO:(CH₃)₂HSi—O—SiH(CH₃)₂).
 10. A semiconductordevice manufacturing method according to claim 6, wherein a firstelectrode and a second electrode of a parallel-plate type are providedas means for plasmanizing the film forming gas, and, when a film isformed, a high frequency power having a frequency of 1 MHz or more isapplied to the first electrode and a low frequency power having afrequency of 100 kHz to 1 MHz is applied to the second electrode whichthe substrate is loaded.
 11. A semiconductor device manufacturing methodaccording to claim 6, after the step of forming the protection layer forcovering the coating insulating film, further comprising the steps of:forming an opening portion in the protection layer for covering thecoating insulating film, the coating insulating film, and the protectionlayer for covering the first wiring; and forming a second wiring toconnect the first wiring via the opening portion.
 12. A semiconductordevice manufacturing method according to claim 11, after the step offorming the second wiring, further comprising the step of: forming aprotection layer for covering the second wiring by plasmanizing a thirdfilm forming gas to react, wherein the third film forming gas includesany one selected from a group consisting of alkoxy compound having Si—Hbonds and siloxane having Si—H bonds and any one oxygen-containing gasselected from a group consisting of O₂, N₂O, NO₂, CO, CO₂, and H₂O. 13.A semiconductor device manufacturing method according to claim 12,wherein the third film forming gas further includes any one selectedfrom a group consisting of N₂ and H₂.
 14. A semiconductor devicemanufacturing method according to claim 12, wherein the alkoxy compoundhaving Si—H bonds constituting the third film forming gas is formed oftrimethoxysilane (TMS:SiH(OCH₃)₃).
 15. A semiconductor devicemanufacturing method according to claim 12, wherein the siloxane havingSi—H bonds constituting the third film forming gas is formed oftetramethyldisiloxane (TMDSO:(CH₃)₂HSi—O—SiH(CH₃)₂).
 16. A semiconductordevice manufacturing method according to claim 12, wherein a firstelectrode and a second electrode of a parallel-plate type are providedas means for plasmanizing the film forming gas, and, when a film isformed, a high frequency power having a frequency of 1 MHz or more isapplied to the first electrode and a low frequency power having afrequency of 100 kHz to 1 MHz is applied to the second electrode whichthe substrate is loaded.
 17. A semiconductor device comprising: (i) asubstrate having (a) a coating insulating film containing at least anyone selected from the group consisting of a silicon-containing organiccompound and a silicon-containing inorganic compound in a surface of thesubstrate; and (ii) a protection layer for covering the coatinginsulating film to contact the coating insulating film, wherein theprotection layer for covering the coating insulating film is asilicon-containing insulating film which has a peak of an absorptionintensity of an infrared rays in a range of a wave number 2270 to 2350cm⁻¹, a film density in a range of 2.25 to 2.40 g/cm³ ₁ and a relativedielectric constant in a range of 3.3 to 4.3.
 18. A semiconductor deviceaccording to claim 17, further comprising a first wiring and aprotection layer for covering the first wiring to contact the firstwiring, that are provided on a surface of the substrate, wherein theprotection layer for covering the first wiring is a silicon-containinginsulating film which has a peak of an absorption intensity of aninfrared rays in a range of a wave number 2270 to 2350 cm⁻¹, a filmdensity in a range of 2.25 to 2.40 g/cm³, and a relative dielectricconstant in a range of 3.3 to 4.3.
 19. A semiconductor device accordingto claim 18, further comprising a second wiring on an interlayerinsulating film which consists of the protection layer for covering thefirst wiring, the coating insulating film on the protection layer forcovering the first wiring, and the protection layer for covering thecoating insulating film.
 20. A semiconductor device according to claim19, further comprising an opening portion formed in the interlayerinsulating film and a sidewall protection layer on a sidewall of theopening portion, wherein the second wiring contacts the first wiringthrough the opening portion, and the sidewall protection layer is asilicon-containing insulating film which has a peak of an absorptionintensity of an infrared rays in a range of a wave number 2270 to 2350cm⁻¹, a film density in a range of 2.25 to 2.40 g/cm³, and a relativedielectric constant in a range of 3.3 to 4.3.